462 Frederick Guthrie on Eutexia. 



every case, no matter what liquid is employed, the amount of 

 rise in the tube will give the volume, and therefore the 

 weight of water which the solid would displace. The rule 

 for finding the specific gravity is always the same : — Divide 

 the weight of substance in air by the number of grains or 

 grammes read off upon the burette. 



For entering into a detailed description of so simple a 

 contrivance, we make this apology. It is to be regretted, 

 both on scientific and practical grounds, that chemists so 

 seldom determine the physical constants of the numberless 

 new salts and other substances which pass through their 

 hands. The reason undoubtedly is that physical experi- 

 mental methods are usually both troublesome and tedious. 

 We have endeavoured to simplify one of the simplest and 

 most beautiful of these methods, and shall be pleased if the 

 apparatus we have described should facilitate the systematic 

 description of the physical properties of new substances. 



Chemical Laboratory, University of Glasgow, 

 April 2, 1884. 



L1I. On Eutexia. By Frederick Guthrie*. 



VII. 

 INTRODUCTION.— Although this memoir does not treat 

 directly of the relationship between water and salts, the 

 subject is so analogous with that examined in my memoirs on 

 " Salt-Solutions and Attached Water," that I have numbered 

 the paragraphs in sequence with those of memoir VI. on that 

 subject (Phil. Mag. vol. vi. p. 115). 



The main argument of the present communication hinges 

 upon the existence of compound bodies, whose chief charac- 

 teristic is the lowness of their temperatures of fusion. This 

 property of the bodies may be called Eutexia t, the bodies 

 possessing it eutectic bodies or eutectics (ev rrjiceiv). It is 

 at once apparent that the cryohydrates are essentially eutectic. 

 It will, however, perhaps be better to make the term more 

 useful by limiting its application. I shall use it, and I should 

 like it to be used by others, for bodies made up of two or more 

 constituents, which constituents are in such proportion to one 

 another as to give to the resultant compound body a minimum 

 temperature of liquefaction — that is, a lower temperature of 



* Communicated by the Physical Society. Read May 24, 1884. 



t Used in very much this sense by Aristotle. I should have preferred 

 the word hypolytic ; but I am instructed that, although sanctioned by its 

 use in Chemistry, this employment of viro is not strictly admissible. 



